Scientific

Specific Gravity

Definition

The dimensionless ratio of a substance’s density to the density of a reference substance, typically water at 4°C (999.97 kg/m³) for liquids and solids.

Explanation

Gold has a specific gravity of 19.3, meaning it is 19.3 times denser than water. Ice has a specific gravity of 0.917, which explains why it floats (any value below 1.0 floats in water). Specific gravity equals density in g/cm³ for liquids and solids, since water’s density is approximately 1.000 g/cm³ at 4°C. Brewers use specific gravity (typically 1.040–1.060 for wort) to estimate alcohol content after fermentation.

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